Guys, thank you very much for all your responses. I must admit that after reading the first few answers some time ago, and seeing that it's an unclear situation, i forgot about this thread.
I am surprised it's really like that.
So you can plug a 15 amp rated power strip into a 20 amp outlet, plug in some devices and have it running at 20 amp summarized load with breaker not moving and the wire overloaded by 33% ??
For the machine (designed to be ran on a nema 5-15 or 5-20 outlet), we decided to use #14 wire and put a 15 amp fuse right at our infeed, so we protect the cord even when plugged into a 20 amp.
But doesn't this topic lead to melting cheap power strips used on 20 amp outlets all the time? What's the US standard gauge for an average 5 or 6way residental power strip?
And what is your maximum permitted current for a non-fixed appliance on 5-15 (for example a vacuum cleaner, electric bbq or whatever)??
We also do have power strips with thermal problems, but usually they only melt when constantly overloaded. Our standard outlet is 16 amp, but only few people know it's officially "16 amp intermittent, 10 amp permanent" so they use a power strip to run two 2000 watt appliances, which is just under 20 amp and might never trip the 16a breaker.
Last edited by andey; 05/26/15 12:31 PM.